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Outbreak That Wasn't: A SARS False Alarm

It seemed like the typical viral ''summer cold'' as it began spreading through a nursing home in the Vancouver area in early July. Then in August, test results from the Canadian National Microbiology Laboratory suggested that the ''cold'' might be from a mutated SARS coronavirus.

Just the hint created deep concerns in a country that had already been hobbled by an outbreak in Toronto last spring. British Columbia officials temporarily imposed infection control and quarantine measures that had contained the Toronto outbreak.

The disruptive and costly actions turned out to be excessive. British Columbia officials have since determined that the SARS coronavirus did not cause the outbreak. Rather, they said, its virological cousin, the OC43 coronavirus, which commonly causes colds, was the probable culprit.

Disputes among Canadian officials over the virological findings have exposed deep flaws in the systems available to detect and monitor any potential outbreak in Canada and elsewhere. Not only did they underscore the need for more uniform laboratory testing, but also prompted health officials to renew calls for reliable tests to detect SARS, or severe acute respiratory syndrome, in its earliest stages of infection.

''The safety net for detecting the possible return of SARS is pretty fragile,'' said Dick Thompson, a spokesman for the World Health Organization, the United Nations agency in Geneva with responsibility for controlling the disease. ''It holds together, but it is spit and luck.''

Examination of the disputed findings in Canada is also occurring as the world is bracing for the possible resurfacing of SARS. A recent report from the United States National Intelligence Council -- which consists of experts from the academic and private sectors and which reports to the director of central intelligence, George J. Tenet -- lays out three bleak possible situations for the virus's re-emergence. Surprisingly, the intelligence report does not consider an instance in which the disease does not reappear.

The three situations outlined in the report are disconcerting. One is a resurgence in countries with major trade centers as international travelers spread SARS the way they did this year. A second is that SARS cases will occur sporadically but will be detected before the disease can spread, creating more of a public health nuisance than a crisis. The third unfolds in developing countries with weak public health systems.

All make early detection a priority. Canadian and United States health officials and SARS experts are expected to discuss what steps may reliably be taken to identify possible new SARS cases, among other topics, at a two-day closed meeting in Ottawa that begins tomorrow.

To some health officials, the outbreak at the Kinsmen Place Lodge nursing home in Surrey, British Columbia, has not only revealed important gaps that need to be addressed, but it may also provide lessons that can be used in the face of a recurrence of SARS.

''In a way, it was lucky that this outbreak happened before the influenza season because it is better to learn about the problems now than then,'' said Dr. Katrin Leitmeyer, a W.H.O. epidemiologist and virologist who went to the National Microbiology Laboratory in Winnipeg to review its findings.

One of the most glaring problems uncovered by the nursing home outbreak was the absence of a formal agreement among scientists about precisely what steps and laboratory methods should be used to make a definitive diagnosis of SARS.

For example, many test results remain in dispute, largely because the scientists involved in different laboratories did not use the same methods to test each specimen to try to identify the virus and to determine whether the patients' immune systems had produced antibodies against it. And partly because little is left of the specimens collected from the nursing home patients, it will take weeks more to prove that the suspected OC43 coronavirus, is the cause.

The conflicting laboratory results have led Canadian scientists and officials to clash over the validity and meaning of the tests performed on the lodge residents and staff members.

''We're at loggerheads with the National Microbiology Laboratory,'' said Dr. Mel Krajden, the chief virologist at the British Columbia Center for Disease Control.

The center's chief epidemiologist, Dr. David Patrick, said that from July 1 through August, 95 of the 142 lodge residents, or 67 percent, developed the summer cold and that 8 deaths were related to the outbreak. Of the 160 health workers there, 53, or 33 percent, developed the summer flu.

Initially, Dr. Krajden's team found no evidence of viruses like influenza, parainfluenza and respiratory syncytial virus that are common causes of upper respiratory illness.

SARS was low on the candidate list because the death rate among lodge residents was 8 percent, far lower than the rate of 50 percent or more found among people 60 and older in the SARS epidemic last spring.

But when a second wave struck the nursing home and the center still could not identify a virus, health officials reconsidered SARS. ''So, having come up empty-handed, we said why not send some of the very limited remaining materials to'' the national laboratory, Dr. Krajden said.

It was a step that many laboratories less concerned about the threat of SARS might not have taken under the same circumstances, health officials said.

The surprise came when Dr. Frank Plummer, the director of the National Microbiology Laboratory, said that his team had found tentative evidence of what might be a mutant SARS virus.

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Then on Aug. 22, provincial officials said the latest findings from the British Columbia Center for Disease Control and the British Columbia Cancer Agency's Genome Sciences Center ''provide conclusive evidence'' that the virus responsible for the nursing home outbreak was not the SARS coronavirus, but probably its cousin, OC43.

''We have clearly found large sequences of the virus that are not present in the SARS coronavirus,'' Dr. Patrick said.

Last week, Dr. Larry J. Anderson, an expert on respiratory diseases at the Centers for Disease Control and Prevention in Atlanta, said his team had completed tests to detect antibodies to the SARS virus in the blood specimens sent by Dr. Plummer. The C.D.C. tests did not confirm the Canadian National Microbiology Laboratory findings that SARS antibodies were present.

Dr. Plummer said he agreed that the virus was not the classic SARS virus, but that his team had found no evidence of OC43.

''We do not dispute their results, but we also believe our results,'' Dr. Plummer said. ''Now what produced them is a puzzle.''

Among the possible explanations for the conflicting results is that two or more viruses were simultaneously affecting the nursing home. Another possibility is that the specimens from the lodge were inadvertently contaminated with SARS virus in the Winnipeg laboratory. Dr. Plummer said he considered that unlikely because of the pattern of his test findings. ''All these diagnostic tests are new and every laboratory has developed its own test,'' he said.

''We have a limited understanding of their performance, so comparing what one laboratory is talking about to another is problematic,'' Dr. Plummer said. ''This is obviously new territory for all of us. We are probably at a normal state of development for a disease that has been around for a few months, and we will be learning every time one of these things happen.''

The Canadian laboratories have not succeeded in growing the nursing home virus and then fully mapping its genome -- two findings that would provide the most definitive evidence of the causative agent. But virologists say that growing the coronavirus apparently involved in the nursing home outbreak is more difficult than growing the SARS virus in the laboratory.

The threat of SARS may prompt several changes in laboratory practices, virologists said. For example, diagnostic laboratories rarely include coronaviruses in screening tests for the cause of outbreaks of respiratory illness because they generally cause mild illness and because budgets preclude searching for every virus.

''No one ever cared that much,'' said Dr. Kathryn V. Holmes, a professor of microbiology at the University of Colorado Health Sciences Center in Denver who has studied coronaviruses for 20 years. She was not involved in the Canadian investigation.

And the nursing home developments raise questions about how research is conducted in a public health crisis, said Dr. Roland Guasparini, chief medical health officer of the Fraser Health Authority near Vancouver, which had jurisdiction over the nursing home outbreak.

Dr. John MacKenzie, an Australian virologist who is temporarily helping W.H.O. deal with the threat of SARS and other emerging diseases, said the nursing home episode pointed out three major worries about laboratory testing for SARS that an advisory panel of W.H.O. would need to address in October.

One is the lack of quality assurance. The various methods have not been tested in different laboratories under different conditions, Dr. MacKenzie said, and ''this is a big concern.''

Second, there is no internationally accepted standardization of the biological materials known as reagents used in testing in different laboratories. Dr. MacKenzie said he was particularly concerned about the lack of standardization of the control tests, which play a routine part in laboratory testing.

Third, Dr. MacKenzie said, ''we need to look very carefully at what we do if we have a positive case.''

''What's crucial is that a second laboratory, preferably an international reference laboratory outside the country that found the positive, confirms the tests,'' Dr. MacKenzie said. ''Some countries are not keen on this,'' he added, yet ''it is a major issue.''

At the October meeting, he said, ''We're going to go into detail about what is known, what isn't known, what needs to be done, and then prioritize some things that need to be looked at.''

But because the W.H.O. meeting will not be held until late October, it may be too late to be effective, Mr. Thompson, the agency spokesman, acknowledged.

By then the Northern Hemisphere may be experiencing the usual seasonal outbreaks of influenza and other respiratory illnesses. Under such circumstances, the continuing lack of a reliable diagnostic test for SARS could create chaos from the continuing inability to distinguish SARS from other illnesses that, by coincidence, were producing similar symptoms like fever, headache and cough.